Oxygen isotopic composition of micrometer-sized quartz grains in EPICA-Dome C ice core

Depicting the geographic provenance of aeolian dust reaching the interior of the East Antarctic plateau is of primary importance for a thorough underst94anding of paleo-atmospheric circulation patterns. A geochemical approach based on the 87Sr/86Sr versus 143Nd/144Nd isotopic signature of mineral particles extracted from Antarctic ice cores and comparison with samples from the Potential Source Areas (PSA) of the Southern Hemisphere has been classically used. This allowed pointing out a dominant Southern South American provenance for dust in the EPICA-Dome C and Vostok ice cores during late Quaternary glacial stages. However, the Sr-Nd isotopic fields from other potential source regions did show a partial overlap with the South American and glacial dust fields, and complementary arguments had to be invoked to infer that their possible contribution is negligible. In this study, we propose a new approach for dust fingerprinting based on the 18O/16O ratios of micrometer- sized quartz grains (1 to 2 μm in size) entrapped in Antarctic ice. Micrometric quartz grains were first identified through SEM/EDX in a sample from the EPICA-Dome C ice core dating back the last glacial maximum. O-isotopic measurements on 25 single grains were performed with the NanoSIMS ion microprobe at the Max-Plank-Institute for Chemistry in Mainz. 18OSMOW values are between 2 and 43 per mil; however most 18OSMOW values fall within a gaussian distribution with a mean 18OSMOW of 25.5 per mil and standard deviation of 2.6 per mil (1^3). These results suggest that a significant contribution from Australian and New Zealand sources seems very unlikely during glacial stage 2, but unfortunately 18OSMOW values for small quartz grains from the Southern Hemisphere PSAs are very scarce. NanoSIMS O-isotopic measurements on Aeolian quartz grains entrapped in Antarctic ice by is a promising tool for investigating the geographic provenance of mineral dust in Quaternary times.